Well-tool grab



March 18, 1930. G. A. ROBISON WELL TOOL GRAB Filed April 30, 1928 INVENTOR.

BY ffiga f? ATTORNEYS.

Patented Mar. 18, 1930 PATENT OFFICE GEORGE A. ROBISON, OF BAKERSFIELD, CALIFORNIA WELL-TOOL GRAB Application filed April 30, 1928. Serial No. 274,002.

This invention relates to a grappling device designed for engaging and recovering tools lost in a well bore.

The primary object of this invention is to provide, in a manner as hereinafter set forth,

a grapple which can be controlled from the mouth of the well to positively grip the tool and is not dependent for its action upon any jarring action or the activity of resilient devices of any character.

Another object of the invention is to provide a grab or fishing tool so designed that in the event of the breakage of any one of the ipping elements forming a part thereof or t e pivot member holding the element in place, the same will not be lost but can be withdrawn from the well for repair or replacement.

Other objects and advantages of the present invention will become apparent as the description of the same proceeds, and the invention will be best understood from a com sideration of the accompanying drawings formin a part of the present invention, with the un erstanding, however, that the invention is not confined to any strict conformity with the showing of the drawing but may be changed or modified so long as such changes or modifications mark no material departure so from the salient features of the invention as expressed in the appended claims.

In the drawing: V

t Figure 1 shows the tool embodying the present invention, in side elevation;

Figure 2 is a transverse section taken upon the line 22 of Figure 1. 4

Figure 3 is a sectional view taken upon the line 33 of Figure 1.

F i re 4 is a transverse section taken upon the line 44 of Figure 1.

Figure 5 is a transverse sectlon taken upon the line 5-5 of Figure 1.

Referring now to the drawing in detail, wherein like numerals of reference indicate corresponding parts throughout the several views, the present improved grab comprises a main or center shaft indicated as a whole by the numeral 1, which shaft is divided into two sections, the upper or main body portion 2 the end of which is screw threaded as indicated at 3, and the reduced elongated stem portion 4 which is provided throughout substantially half its length withleft hand screw threads.

Carried upon the reduced stem 4 at the upper end or the unthreaded portion thereof is a head member indicated as a whole by the numeral 5, which member is provided with the longitudinally extending laterally or radially projecting wings 6, each of which is longitudinally slotted as indicated at 7, and the central longitudinally extending bore or passage 8, through which the stem 4 extends. The top of the body 5 abuts the shoulder which is formed at the point 9 where the stem 4 which is of smaller diameter than the upper portion 2, joins the portion 2. The opposed inner faces of the slots '7 are provided with the parallel grooves or recesses 10 which grooves extend at an angle with respect to the longitudinal axis of the body 5, having their upper ends arranged closer to the center than the lower ends thereof, or in other words diverging downwardly of the member.

The head member 5 is maintained in position at the upper end ofthe reduced portion 4 by a centrally apertured substantially semi-' spherical body 11 through the central aperture of which the stem 4 is passed until the body bears against the under side of the head'member 5 in the manner shown in Figure 1, the curved top surface of this body being upper most as shown to form a camming surface as will be hereinafter more fully described. This camming body 11 while secured to the reduced portion 4 of the stem turns therewith and maintains the head member 5 in position thereon, allowing the stem to rotate in the head.

Threaded upon the lower end of the stem 4 there is an elongated sleeve 12 from which there extends, intermediate the ends thereof, and equi-distantly spaced thereabout, the cars 13.

In order to prevent the sleeve 12 from leaving the stem 4 when the tool is in operation, there is secured to the lower end of the stem the stop collar 14. g

A plurality of elongated gripping arms 15 is provided, which arms are of materially greater length than the reduced stem 4 and each is positioned at its upper end in the slot 7 of the head member 5 and is retained in position therein by the transverse pins 16 each end of each of which pins has sliding engagement in an adjacent groove 10.

The inner edge of each of the gripping arms 15 is provided with a recess conforming to the curvature of and designed to receive the cam body 11, the recess being indicated by the numeral 17. Below each recess 17, each gripping arm 15 has formed therein the pocket 18 which receives one of the ears 13 of the sleeve 12, a pivot or hinge pin 19 being then passed transversely through each arm and through the pocket therein to engage the inserted ear 13, as shown in Figure 4.

The lower or free end of each gripping arm 15 is tapered as shown and terminates in the gripping jaw 20, the inner face of which is serrated as indicated at 21 so that non-slipping engagement can be had with the face of a tool when the four jaws 20 are brought together thereabout.

In the operation of the present tool a suitable number of rods are attached to the threaded portion 3 of the tool and the tool inserted in a well bore. hen the tool has been lowered to the point where the jaws 2O overlie the end of the tool or pipe which is to gripped, the pipe or rod to which the tool is attached is rotated to the rightor in a clockwsie manner, thereby causing the sleeve 12 to move longitudinally of and downwardly on the stem 4. This action is brought about through the frictional engagement of the arms 15 with the wall of the casing or well bore which prevents the entire tool from turning allowing only the control pipe or rod and the central stem 1 of the tool to rotate.

It will be readily understood that with the head member 5 and the arms 15 held from rotation, the rotation of the stem 1 will cause the sleeve to move downwardly in the manner described forcing the curved faces of the recesses 17 to ride over the cam body 11 swinging outwardly the upper ends of the arms 15 and drawing the lower ends thereof together.

This outward movement of the arms being further induced through the movement of the pins 16 downwardly in their guide grooves 10. It will of course be readily understood that in order to release the grab a reverse rotary movement of the stem 1 is brought about thereby returning the arms 15 to their normal position substantially parallel with the stem.

in order to introduce water into the well bore when the grab is being employed, the stem 1 is provided with the longitudinally extending passage 22 through which water can be passed to the lower end of the tool as will be readily apparent.

From the foregoing description it will be readily seen that the herein described tool can be made strong and durable, is not clumsy in construction, exerts a positive and powerful gripping action, and is easily and quickly actuated.

Having thus described my invention what I claim is:

1. A tool grab comprising a head member, a stem extending through and rotatably supported by the head member, a sleeve arranged below the head member and screw threadedly engaged with the stem for downward movement with respect to the head member on the turning of the stem in one direction, arms connected between their ends to the sleeve for movement therewith and for pivotal movement with respect thereto, and means associated with the head member and the upper ends of the arms for swinging the lower ends of the arms inwardly during the downward movement of the arms.

2. A tool grab comprising a head memher, a stem extending through and rotatably supported by the head member, a sleeve arranged below the head member and screw threadedly engaged with-the stem for downward movement with respect to the head member on the turning of the stem in one direction, arms-connected between their ends to the sleeve for movement therewith and for pivotal movement with respect thereto, means connecting the upper ends of the arms to the head member for downward and outward movement with respect to the head member, and means associated with the stem and the arms for swinging the lower ends of the arms inwardly during the downward movement of the arms.

3. In a well tool grab of the character described, a plurality of elongated normally parallel arms, a head member, means for pivotally and slidably connecting one end of each of said arms to said head, a rotating stem, means carried upon and designed to move longitudinally on said stem for pivotally connecting said arms intermediate their ends, and means whereby upon the movement of said stem carried connecting means said arms will be caused to move longitudinally of the stem and will have their free ends shifted relative to one another for gripping or releasing action.

4. A well tool grab, comprising a plurality of elongated normally parallel gripping arms, a head member, means for slidably and pivotally attaching one end of each-of said arms to said head, an elongated stem having said head member rotatably mounted thereon and having a portion of one end screw threaded, a sleeve member threaded upon the threaded end of said stem and having pivotal connection with each of said arms intermediate the ends of the same, and means carried by said stem and acting upon said arms whereby the free ends of the arms will be shifted relative to one another upon the rotation of the stem and the movement of said sleeve longitudinally thereon.

5. A tool grab of the character described, comprising a plurality of elongated gripping arms, a centrally apertured head member having the wall thereof provided with a plurality of longitudinally extending radially opening slots each designed to receive one end of an arm, means for pivotally connecting one end of each arm in a slot to permit its movement longitudinally of the slot, an elongated stem body extending through said head and terminating at one end between said arms, and having that end provided with screw threads, a sleeve body threadably mounted upon said stem, pivotal connecting means between said sleeve and the arms, intermediate the ends of the same, and a cam member carried upon said stem and acting upon said arms when the same are moved longitudinally of the stem through the movement of said sleeve thereon, to swing the free ends of the arms relative to one another.

In testimony whereof I aflix my signature.

GEORGE A. ROBISON. 

